From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S264132AbTDJTwx (for ); Thu, 10 Apr 2003 15:52:53 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S264133AbTDJTwx (for ); Thu, 10 Apr 2003 15:52:53 -0400 Received: from h68-147-110-38.cg.shawcable.net ([68.147.110.38]:47345 "EHLO schatzie.adilger.int") by vger.kernel.org with ESMTP id S264132AbTDJTww (for ); Thu, 10 Apr 2003 15:52:52 -0400 Date: Thu, 10 Apr 2003 14:04:00 -0600 From: Andreas Dilger To: Lorenzo Allegrucci Cc: linux-kernel@vger.kernel.org Subject: Re: ext2/3 fragments support Message-ID: <20030410140400.G26054@schatzie.adilger.int> Mail-Followup-To: Lorenzo Allegrucci , linux-kernel@vger.kernel.org References: <200304102135.19381.l.allegrucci@tiscali.it> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5.1i In-Reply-To: <200304102135.19381.l.allegrucci@tiscali.it>; from l.allegrucci@tiscali.it on Thu, Apr 10, 2003 at 09:35:19PM +0000 X-GPG-Key: 1024D/0D35BED6 X-GPG-Fingerprint: 7A37 5D79 BF1B CECA D44F 8A29 A488 39F5 0D35 BED6 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Apr 10, 2003 21:35 +0000, Lorenzo Allegrucci wrote: > Fragments support on ext2/3 filesystems seems disabled > or non fully functional. > Are there any plans to implement fragments? They have never been enabled. The "goal" is to imlement fragments as a type of extended attribute, so that they can be packed into a single block or inline in a larger inode (along with other EA data) instead of being fixed-size hunks. The first thing that needs doing is fixing the current ext2/3 EA sharing scheme, which currently only shares blocks if they are identical and is therefore only really useful for ACLs. The best proposal so far for EA sharing is to put them into a directory-like structure (maybe one dir per block group or something) and have the EA type and data be packed inline into the directory (like the inode number and filename are done with regular directories). Each inode would also have a "catalog" of the EAs that it has (itself an EA, either inline in a larger inode or in the directory pointed to by, say, i_faddr). Shared entries would be like hard links pointed to by mutliple catalogs, with a refcount. This was discussed on ext2-devel about a year ago, but no takers on the implementation yet (I might eventually need to implement it this year if nobody beats me to it, because we need better EAs than one per 4kB of disk). Cheers, Andreas -- Andreas Dilger http://sourceforge.net/projects/ext2resize/ http://www-mddsp.enel.ucalgary.ca/People/adilger/